Background: Urinary tract infections (UTIs) are common among women and frequently recur. Depletion of vaginal lactobacilli is associated with UTI risk, which suggests that repletion may be beneficial. We conducted a double-blind placebo-controlled trial of a Lactobacillus crispatusintravaginal suppository probiotic (Lactin-V; Osel) for prevention of recurrent UTI in premenopausal women.

Methods: One hundred young women with a history of recurrent UTI received antimicrobials for acute UTI and then were randomized to receive either Lactin-V or placebo daily for 5 days, then once weekly for 10 weeks. Participants were followed up at 1 week and 10 weeks after intervention and for UTIs; urine samples for culture and vaginal swabs for real-time quantitative 16S ribosomal RNA gene polymerase chain reaction for L.crispatus were collected.